The objective of the proposed research is to determine the nature of abnormalities in Cerebral Blood Flow and Metabolism associated with major psychiatric disorders (schizophrenia and affective disorders) and to evaluate the effects of chemotherapy on these abnormalities. Schizophrenics and patients with affective disorders who were not exposed to antipsychotic medication regimens will be examined using Positron Emission Transaxial Tomography (PETT) to determine local cerebral blood flow (LCBF), local cerebral metabolism rates for oxygen (LCMRO2) and local cerebral metabolism rates for glucose (LCMRgl). All measurements will be done under baseline conditions and LCBF will also be determined during cognitive activity. In addition, comprehensive clinical and neuropsychological measurements will be conducted in order to establish the relationship between brain activity patterns and behavioral manifestations of the disorders, and Computerized Axial Tomography (CAT) scans will be obtained to establish precise localization of activity levels and to evaluate neuroanatomical abnormalities in the psychiatric patients. These measurements will be repeated after four months, when the patients are stabilized on medication.